wifi: mac80211: add API to parse multi-link element

Add the necessary API to parse the multi-link element in
the future. For now, link only to the element when found
so we can use it in the client-side code later.

Later, we'll need to fill this in to deal with element
fragmentation, parse the STA profile, etc.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -1658,6 +1658,7 @@ struct ieee802_11_elems {
 	const struct ieee80211_aid_response_ie *aid_resp;
 	const struct ieee80211_eht_cap_elem *eht_cap;
 	const struct ieee80211_eht_operation *eht_operation;
+	const struct ieee80211_multi_link_elem *multi_link;
 
 	/* length of them, respectively */
 	u8 ext_capab_len;
@@ -2161,6 +2162,8 @@ static inline void ieee80211_tx_skb(struct ieee80211_sub_if_data *sdata,
  * @bss: the BSS to parse this as, for multi-BSSID cases this can
  *	represent a non-transmitting BSS in which case the data
  *	for that non-transmitting BSS is returned
+ * @link_id: the link ID to parse elements for, if a STA profile
+ *	is present in the multi-link element, or -1 to ignore
  */
 struct ieee80211_elems_parse_params {
 	const u8 *start;
@@ -2169,6 +2172,7 @@ struct ieee80211_elems_parse_params {
 	u64 filter;
 	u32 crc;
 	struct cfg80211_bss *bss;
+	int link_id;
 };
 
 struct ieee802_11_elems *
@@ -2186,6 +2190,7 @@ ieee802_11_parse_elems_crc(const u8 *start, size_t len, bool action,
 		.filter = filter,
 		.crc = crc,
 		.bss = bss,
+		.link_id = -1,
 	};
 
 	return ieee802_11_parse_elems_full(&params);

net/mac80211/util.c

@@ -1022,6 +1022,10 @@ static void ieee80211_parse_extension_element(u32 *crc,
 		if (ieee80211_eht_oper_size_ok(data, len))
 			elems->eht_operation = data;
 		break;
+	case WLAN_EID_EXT_EHT_MULTI_LINK:
+		if (ieee80211_mle_size_ok(data, len))
+			elems->multi_link = (void *)data;
+		break;
 	}
 }
 
@@ -1524,6 +1528,7 @@ ieee802_11_parse_elems_full(struct ieee80211_elems_parse_params *params)
 			.start = nontransmitted_profile,
 			.len = nontransmitted_profile_len,
 			.action = params->action,
+			.link_id = params->link_id,
 		};
 
 		_ieee802_11_parse_elems_full(&sub, elems, NULL);